This invention relates to a pump chamber for an intravenous or blood pump of the positive displacement type. More particularly, this invention relates to a pump chamber cassette for an intravenous pump wherein a diaphragm is moved inwardly by a driver element to force blood out of a cavity and through a biased outlet valve which is designed to substantially reduce blood hemolysis.
The pump chamber of this invention is fabricated to be employed in a pumping device of the type described in U.S. Pat. No. 3,620,650. The basic pump cassette of which this cassette is an improvement is currently being marketed by Abbott Laboratories of North Chicago, Ill. in an I.V. pump under the name Abbott/Shaw Life Care Pump. Some problems have been encountered in utilizing the currently marketed cassette in connection with the pumping of blood. As indicated in U.S. Pat. No. 3,620,650, a biased outlet valve is employed with a biasing means in the form of an exposed spring. The same is true of the unit being marketed currently which employs a ball with the spring. When blood is pumped through the biased ball outlet valve having an exposed spring member, high shear pressure is effected because of the geometric configuration of the valve seat and valve member and the spring which is exposed to fluid flow. When packed red cells are administered through the current cassette, the shear velocity and contact with the spring causes excess hemolysis of the cells.
It is an advantage of the present invention to provide a novel pump chamber cassette for an I.V. positive displacement pump useful for administering blood. Other advantages are a pump chamber for a blood administration set pump which substantially reduces hemolysis during administration; a unique biased outlet valve member in the outlet passage of the pump chamber cassette; a pump cassette which can be manufactured at low cost so as to not add an appreciable amount of cost to an intravenous adminstration set, yet can administer I.V. solutions as well as blood.